Lower extremity sprain injuries and related microtrauma often result from poorly managed torsion strain in the affected ankle or knee joints. Overweight individuals often suffer knee injuries from repeated torsion strain when walking as they turn to change directions. This occurs when they pivot their feet while wearing shoes that hold fast to the average firm walking surface, and when weakness in the posterior lower extremity impedes lifting their heels while pivoting. Repeated episodes of pivoting torsion stress coupled with the heavy weight injuries supportive ligaments. Previous treatment methods for these injuries utilized elastic devices that wrapped around the involved joint. Such devices splinted the injured joint but did not reduce the offending torsion inside the joint.
A review of prior art discloses a history of interest in various roller devices to assist in propulsion, not for therapeutic goals, but for recreational purposes, including two wheeled U.S. Pat. No. 4,844,492; three wheeled U.S. Pat. No. 4,523,767; and four wheeled U.S. Pat. No. 3,900,203. These known devices cannot be used to reduce torsion strain of the knee and ankle. Another recreational roller skate U.S. Pat. No. 4,303,253 allowed a person to pivot on the ball of the foot, but it could not be used for walking.
Other prior art devices dealt with shoe heel function. These devices such as the cushioning springs of U.S. Pat. No. 4,296,557; conical springs in U.S. Pat. No. 4,342,158; and leaf spring in U.S. Pat. No. 4,566,206 attempted to reduce the vertical compression strain of running, but did little to reduce torsion strain in the ankle or knee for overweight people in normal walking situations. Prior art also discloses shoe heel devices to alter heel wear, such as U.S. Pat. No. 3,478,447 but did not reduce lower extremity torsion.